title: Norovirus: a growing cause of gastroenteritis in catalonia (Spain)?
abstract: Infectious acute gastroenteritis (AGE) is a major health problem worldwide. Salmonella is a leading cause of AGE outbreaks, but viruses may be responsible for up to 80% of cases. We compared the frequency and characteristics of AGE out breaks in Catalonia due to norovirus and Salmonella and the changes in these outbreaks from 2000 through 2010. In 2006 through 2010, we also investigated the distribution by season, setting, and implicated food, the incidence rates of cases associated, and the hospitalization rates. Differences in proportions were estimated by Pearson's chi-square test, and the odds ratio (OR) and 95% confidence interval (CI) were calculated. In 2000 through 2010, the number of AGE outbreaks caused by Salmonella decreased and those caused by norovirus significantly increased. From 2006 onward, norovirus was the most common etiology in AGE outbreaks, but in foodborne outbreaks, Salmonella was the more common cause until 2010. The incidence rate per 10(5) inhabitants was greater for norovirus (20.81 versus 3.97, P < 0.001), and the hospitalization rate was lower for norovirus (0.84 versus 4.69, P < 0.001). Salmonella infections occurred more frequently in the warmer months, and norovirus infections were more common in the colder months, both in terms of total outbreaks (OR = 4.50; 95% CI, 2.85 to 7.11; P < 0.001) and foodborne outbreaks (OR = 4.38; 95% CI, 2.42 to 7.95; P < 0.001). Norovirus infections were less common in private homes (OR = 0.08; 95% CI, 0.04 to 0.14; P < 0.001) and more common in nursing homes (P < 0.001) and hospitals or long-term care facilities (OR = 14.09; 95% CI, 3.35 to 59.33; P < 0.001). Foods most frequently implicated in norovirus infection outbreaks were seafood (22% ; OR = 7.89; 95% CI, 2.59 to 24.3; P < 0.001), and those most common in Salmonella infection outbreaks were mayonnaise and similar items (30.2%; OR = 0.05; 95% CI, 0.01 to 0.22; P < 0.001). Foodborne outbreaks in which the vehicle was not identified were more frequent in cases of norovirus infection (OR = 4.59; 95% CI, 2.54 to 8.30; P < 0.001). Our results indicate that norovirus rather than Salmonella is the most common cause of AGE outbreaks in Catalonia. Foodborne AGE outbreaks were more commonly caused by norovirus than by Salmonella only in 2010, the last year of the study.
authors.affiliation: Public Health Agency of Catalonia, Generalitat of Catalonia, Roc Boronat 81-95, Barcelona 08005, Spain;, Email: a.martinez@gencat.cat.
authors.forename: A
authors.initials: A
authors.lastname: Martínez
authors.forename: N
authors.initials: N
authors.lastname: Torner
authors.forename: S
authors.initials: S
authors.lastname: Broner
authors.forename: R
authors.initials: R
authors.lastname: Bartolomé
authors.forename: S
authors.initials: S
authors.lastname: Guix
authors.forename: M
authors.initials: M
authors.lastname: de Simón
authors.forename: P
authors.initials: P
authors.lastname: Godoy
authors.forename: A
authors.initials: A
authors.lastname: Moreno
authors.forename: M
authors.initials: M
authors.lastname: Company
authors.forename: P J
authors.initials: PJ
authors.lastname: Balanyà
authors.forename: M R
authors.initials: MR
authors.lastname: Sala
authors.forename: R
authors.initials: R
authors.lastname: Torra
authors.forename: G
authors.initials: G
authors.lastname: Ferrús
authors.forename: I
authors.initials: I
authors.lastname: Parrón
authors.forename: I
authors.initials: I
authors.lastname: Barrabeig
authors.forename: A
authors.initials: A
authors.lastname: Domínguez
mesh_terms: D000208:Acute Disease; D000328:Adult; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000635:transmission; D002675:Child, Preschool; D003428:Cross Infection; D004196:Disease Outbreaks; D005759:Gastroenteritis / Q000453:epidemiology* / Q000382:microbiology / Q000821:virology; D006760:Hospitalization; D006761:Hospitals; D006801:Humans; D008297:Male; D029322:Norovirus / Q000302:isolation & purification* / Q000472:pathogenicity; D009735:Nursing Homes; D012475:Salmonella / Q000302:isolation & purification / Q000472:pathogenicity; D012478:Salmonella Food Poisoning / Q000453:epidemiology* / Q000635:transmission; D012621:Seasons; D013030:Spain / Q000453:epidemiology